Measuring Ground Level Ozone - Does the amount of ozone vary with location?
Teaching objectives:
- Constructing (c)I./1:
- Generate scientific questions about the world based on observation
- Design and conduct scientific investigations
- Use scientific tools and equipment
- Use sources of information to support investigation
- Write and follow procedure
- Use metric measurement devices
- Use sources of information to support investigation
- Reflecting (r)11.1:
- Evaluate data
- Show how science applies in real-life context
- Develop an awareness of the natural world
- Hydrosphere: (EH)V.2:
- Describe composition and characteristics of atmosphere
- Describe health effects of polluted air
The Assignment
(1) Click here to visit the Office of Air Quality to learn about ozone pollution. The material may seem a bit below your grade level, but the information is good. Remember to bookmark this site before you leave.(2) Although exposure to sunlight is not a problem for the test strips, excessive exposure can cause them to fade. The four test strips (2 one-hour tests and 2 eight-hour tests) should be gun outside, away from any absorptive surfaces that might react with atmospheric ozone. They should hang at about 1.5 meters off the ground.
(3) Weather data should be record at 12 noon for the ozone readings. Use the weather station at school or a weather network. Construct a data chart like this one below:
| DATE | |
| Relative Humidity (%) | |
| Wind Speed (mph) | |
| Wind Direction | |
| Air Pressure |
(4) After 1 p.m. and before 4 p.m., the test strips should be removed. The one-hour test should be cokplted before 4 p.m. each day. Dip the paper in distilled water. Read the ozone level on the Schoenbein color scale at Judy Lee's Rice University site To prevent further exposure, put transparent tape over both sides of the test strip.
(5) After eight hours of total exposure, two eight-hour readings should be taken. Read the ozone level by using the Schoenbein color scale.
(6) Ozone levels are affected by relative humidity. Find the relative humidity at your site with a bulb psychrometer or local weather data. Use the Rice University's Relative Humidity Number Chart and look on the bottom to find the Schoenbein number you recorded. Draw a line upward that corresponds to your humidity reading. Read the ozone concentration in parts per billion by drawing a perpendicular line from that point to the y axis of the graph.
(7) Data from the tests can be posted at the bulletin board on Judy Lee's site. You can also check UV (ultraviolet levels) at the Rice University site.
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